A conventional method for accomplishing a rapid channel change in a switched digital video network includes streaming beginning at a most recent I-Frame upon receipt of a channel change request by a device in the network. An I-Frame is the first frame in a Group of Pictures (“GOP”) and can be decoded without information from any other decoded video frame. Since a GOP period may be 2 or more seconds, the decoder may disadvantageously begin to receive video that occurred a few seconds in the past. Since the channel change times of viewers are not simultaneous, each viewer will receive a unicast stream based on the location of the I-Frame in the queue on the network device at the time of the channel change request. In order for the decoder to join a multicast stream for the same channel without skipping forward in time, the delay in the network device must be transferred to a delay in the decoder. When all of the delay is in the decoder, then the multicast stream can be joined. The viewer will still see content that may be a few seconds old but this is typically not of consequence to a broadcast video service.
Transferring the delay from the network device to the decoder while simultaneously streaming the video requires the network device to transmit at a faster than normal rate for a period of time. As an example, if a viewer selects a 6 Mbps HDTV program and the most recent I-Frame occurred 2 seconds ago, and further, if the network device is configured to transmit one third faster following a channel change request, then the overall rate is 6*1.33=8 Mbps. To transfer 2 seconds of HDTV delay to the decoder will take 2/0.33=6 seconds.
The capacity of a Digital Subscriber Line (“DSL”) channel is limited. Engineering a network to support rapid channel change as described above requires several Mbps of reserved bandwidth. Such a configuration will either reduce the DSL serving area, reduce the number of video streams that can be delivered, and/or compromise other services during channel changing periods.
A conventional method of rapid channel change consists of temporarily transmitting the video stream at a greater than normal rate as described above. This method is not effective in that additional capacity is required on the DSL line to accommodate rapid channel changes which will either reduce the DSL serving area, reduce the number of video streams allowed, or compromise other services. Therefore, what is desired is an effective system, method, and computer readable medium (or software) to support a rapid channel change in a switched digital video network without, among other things, the need to increase DSL line capacity.